The average time spent online per day by a 15-year-old jumped from

Let me give detailed answer and solve your query as well.

The average time spent online per day by a 15-year-old jumped from 105 minutes to 146 minutes between 2012 to 2015, a difference which shows that smartphones and social media could be partly responsible for the changed behavior of teenagers now a days.

A.spent online per day by a 15-year-old jumped from 105 minutes to 146 minutes between 2012 to 2015, a difference which shows

This is a strong contender, in Non GMAT world it is 100% correct, but GMAT has it's own rules.

Why A is incorrect?

1. "Which" is used here without comma. In GMAT to refer preceded noun by which there must be a comma before "Which"

2. "a difference" after comma is appositive modifier, difference is an abstract noun, it is describing phenomenon mentioned in preceded clause. Use of which to refer "a difference" makes sentence wordy and redundant, however, according to me if which is replaced by that and we do not have option E then it is absolutely correct.

3. If you notice there is one difference between A & E. Active voice vs Passive voice, and if you have gone through OG explanations, there is a word "Rhetoric". Here active voice seems to be rhetorical compared to passive voice.

B.a 15-year-old spends online per day had jumped from 105 minutes to 146 minutes between 2012 to 2015 and showed

We use Past perfect tense only when it is absolutely necessary i.e when sequence of events matters, however, here it is illogical because had jumped and showed... conveys the wrong meaning. Ask this question after reading this answer choice, Who showed?

Parallelism not required here as it is not a list of actions jumped and showed. Wrong! Illogical

C.a 15-year-old spends online per day jumped from 105 minutes up to 146 minutes between 2012 to 2015, showing

Verb+ing modifiers after comma describes the subject of preceding clause. Subject of preceding clause is "a 15-year-old". Does "a 15-year-old" shows that smartphones and social media could be partly responsible for the changed behavior of teenagers now a days. NO! Wrong meaning.


D.between 2012 to 2015, spent online per day by a 15-year-old jumped from 105 minutes to 146 minutes, a difference which showed

Similar to A. Wrong.


E.a 15-year-old spends online per day jumped from 105 minutes to 146 minutes between 2012 to 2015, a difference showing

Correct!

rsrighosh

a 15-year-old spends online per day jumped from 105 minutes to 146 minutes between 2012 to 2015, a difference showing

Spends is verb modifier, which modifies/describe time. Ask which type of time? the time, which a 15-year-old spends online.

jumped is the main verb of the sentence here.

Additionally

"a difference" describes phenomenon mentioned in preceding clause. Abstract noun/Appositive/Noun modifier construction.
"showing" modifies "a difference".

Take aways:

1. Abstract noun/ Appositive modifiers are always preferable in GMAT. But don't fall in love with them, pay more attention to prove them wrong or right.
2."Which" must be used after comma in GMAT to refer preceding noun.
3. Verb+ing modifers after comma always modifiy preceding clause i.e subject/action of preceding clause.
4. Active voice vs Passive voice construction.
5. Correct answer must conveys an intended meaning.

Please reply/quote in case of doubts. Let's discuss and learn.